This R34 study will develop and pilot a smartphone intervention for bipolar disorder. Background: Bipolar disorder is a severe and chronic mental illness that increases mortality and greatly impairs functioning. Psychosocial therapies in combination with medication improve treatment outcomes, but access to psychosocial interventions is limited and only half of bipolar patients receive them. Current therapies also have limitations in terms of: 1) reliance on subjective patient report and 2) difficulties in identifying warning signs of impending episodes. Furthermore, direct measurement of observable daily patterns of behavior is not routinely available, even though alterations in sleep and activity are core symptoms of bipolar disorder. Significance: This project will develop a smartphone intervention for bipolar disorder that will increase access to psychosocial interventions. The use of the phone will allow routine feedback to patients and providers utilizing behavioral data collected by the phone. This should enhance patient self-management of their symptoms and improve treatment outcomes. Innovation: 1) Use of a smartphone to make psychosocial interventions readily accessible to patients during their day-to-day life. 2) Use of a wrist-worn actimeter communicating with the phone to provide consistent collection of activity data relevant to symptom status. 3) Use of the phone to collect novel location and social interaction data relevant to symptom status. 4) Utilizing behavioral data feedback to increase patient symptom self-management and to inform providers for improved evaluation and targeting of treatment. Preliminary studies: Members of the research team have developed algorithms for stratifying patients based on actimetry data and have used mobile phones to measure lifespace which might decrease during depression and expand during mania. The rapid successful development of the system will be facilitated by collaborating with the Center for Behavioral Intervention Technologies, which has substantial expertise in developing and delivering effective psychosocial interventions via smartphones. Design: An iterative, user-centered design process will increase acceptance, participation, and long-term system use by patients and providers. A small randomized controlled trial will test the feasibility of the study protocol (system, recruitment, control, assessment) in preparation for a larger randomized controlled trail. Population: Adult bipolar disorder patients in current remission with a history o two acute episodes in the last two years who are in routine treatment. Outcomes: All aspects of the study protocol will be operationalized in preparation for the subsequent randomized controlled trial. Markers of system use, usability, and satisfaction will be assessed. The primary outcome piloted for the larger study will be percent time symptomatic. Secondary outcomes will include time to relapse, symptom severity, and quality of life.